/* см. https://codepen.io/craigh/pen/reoyje */
input[type=submit] {
  transition: all 0.25s ease, color 1ms;
  text-align: center;
}

input[type=submit]:focus {
  outline: 0;
}

input[type=submit].animate {
    border-radius: 50%;
    background: transparent;
    color: transparent;
    border: 3px solid #337ab7;
    border-left-color: #ccc;
    animation: rotating 2s 0.25s linear infinite;
    animation-delay: 0s;
  width: 34px;
  height: 34px;
}

@keyframes rotating {
  from {
    transform: rotate(0deg);
  }
  to {
    transform: rotate(360deg);
  }
}